Nick Clegg and Jonathan favour amending the succession rules for the monarchy so that the oldest inherits, regardless of sex. My only objection to this is that it doesn't go far enough, and making the correct degree of reform would render this irrelevant. Contrary to popular opinion, we don't have a hereditary monarchy in the UK. We have a selective monarchy, with Parliament choosing who is monarch. And that is not merely some vague theoretical point never enacted in practice.

As recently as the previous monarch - the Queen's father - Parliament preferred someone else (George VI) instead of the hereditary heir (Edward VIII). That's not particularly odd for the English crown. Other famous examples of non-hereditary monarchs include Stephen, Henry IV, Henry VII, Jane Grey, William III, George I, and that is before we get into more complicated cases like James I/VI. Going further back, the pre-Norman conquest English tradition was for the monarch to be selected by the Witan.

For a while it was convenient that the monarch be chosen according to the formulation in the Act of Settlement, to avoid further civil wars after the unpleasantness of the seventeenth century. But since, for the constitutional monarchy to survive, it needs to be more activist - as I argued back in 2002 - and selection would empower the monarch to be more activist, I have for some time argued that the monarch should be chosen by the Upper Chamber - a House of Selectors. Obviously sex would be no bar to such selection.

Having a Catholic Monarch, as David Cameron indicated he favoured in his Today programme interview, is obviously a much greater step. Since the Monarch is, as matters stand, the Supreme Governor of the Church of England, Catholics must, by definition, be banned from the Monarchy (for much the same reason that Protestants are banned from being Pope). So Cameron's proposal that Catholics be permitted to be British monarchs is, straightforwardly, the proposal for disestablishment of the Church of England.

Since I am a fan of establishment, you might therefore assume I would oppose permitting Catholic Monarchs. And indeed I would like to oppose that. But unfortunately (a) a series of court cases and Acts of Parliament have already established that Christianity is no longer the state religion; and (b) I see no appetite in the British Establishment to reverse this. Establishment means more than simply the Queen being Supreme Governor and the odd priest turning up at a coronation. Establishment placed the Protestant religion at the heart of natural law, law-making, the constitution, advice, the moral purpose of society, the resolution of difficult issues, the attitude to wars, and many other topics. The Monarch's role as Supreme Governor was the expression of Establishment, not its defining fact.

Given that Christianity in general and Protestant religion in particular have now been dethroned in the British constitution, it makes little sense for them to remain on the physical throne itself. Indeed, by doing so we pretend that we haven't already disestablished, that our constitution and law is not already actively hostile to Christianity in general and Biblical Protestant religion in particular. Better to be clear, now. Then we can move forward. We might even be more queasy about oppressing Christians if they did not seem like the folks in charge.

So - fine. Have your Catholic monarchs, Wiccan monarchs, frog-worshipping monarchs, or whatever you fancy. Move from opaque de facto (and certainly de jure) disestablishment to overt disestablishment. I have no idea what you propose instead of Protestant Christianity, and I am sorry to say that the likely long-term outcome will be illiberal and unpleasant in a way that would make today's well-meaning secularists blanch. Furthermore, I'm very confident that neither Nick Clegg nor David Cameron has the foggiest idea what they intend to replace Established Protestant religion with.

If we are very lucky, perhaps, in much the same way that many who might casually believe themselves opposed to the monarchy find they like alternatives such as elected or selected Presidents even less once they start to think about it, perhaps if our Establishment is forced to debate explicitly what it might do instead of Christianity, it will see that, in fact, Established Protestant religion has rather a lot going for it as a system. ﻿But I'm not at all hopeful - I fear that the despising of Christianity amongst our elites has become so ingrained, the interventions of senior Anglican churchmen so lame and compromising, and the reluctance of Christian politicians to identify themselves as such so cowardly for so long that there is no way back for Christianity now.

Of course, with the perishing of Established Protestant religion, Conservatism perishes, also. Conservatism is fundamentally a constitutional creed and vision of society built upon orthodox Protestant Christian doctrine. Doubtless the Conservative Party - that wonderfully flexible and ruthlessly power-seeking machine - can survive the death of Conservatism, and will flourish in a new age dominated by secular Democrat concepts.

So today's politicians, few of whom have much comprehension of why anyone would be interested in constitutional Conservatism, and I suspect would imagine that no-one could seriously believe in constitutional Conservatism (that was certainly the case for the Blairites, and I have seen no evidence of any difference on constitutional issues on our side), will shed few tears. Furthermore, the destructive illiberal destiny of secular Democrat conceptions is unlikely to oppress more than a few of us in our lifetimes - there is a lot of ruin in a well-crafted constitution. So, provided I'm all right Jack, and it's just a few loonies waving Bibles that seem upset, I can probably muddle on through and leave the problems to my grandchildren.